Note: Descriptions are shown in the official language in which they were submitted.
21532 C~4
Background of the invention
1. Field of the Invention
This invention relates to an air filtering apparatus for killing and/or
removing
micro-organisms from the air in a space that is unairconditioned or air-
conditioned by cooling, heating or mechanical ventilation system. In
particular, this invention discloses an air filtering apparatus which is
suitable
for use in operating theaters, clinics, laboratories, pharmaceutical
production
1o areas, dispensaries, food processing areas, supermarkets, food outlets,
food
storage areas, offices, public areas such as crowded meeting rooms, toilets,
homes, etc., and generally in rooms where there is a requirement for low
contents of micro-organisms. Micro-organisms, as used in the present
invention, includes but does not excludes bacteria, viruses, molds/fungi, and
yeast.
2. Description of the Related Art
U.K. Patent number GB 2215234 granted to the applicant of the present
invention described an air filtering apparatus having an air-permeable
material disposed within a housing, at least one irradiator downstream of the
air-permeable material disposed within in a radiation chamber for irradiating
the air downstream of the air-permeable material, and a blower downstream
of the irradiator for drawing air through the air-permeable material and the
irradiator, respectively. In the preferred embodiment of GB 2215234, the air-
permeable material comprises a .thick and flat filter having a planar surface
which is substantially orthogonal to the flow of the air through the prior art
air
filtering apparatus. The GB 2215234 air-permeable material is effective in
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removing micro-organisms from the air with irradiator of appropriate
radiation strength. However, air filtering apparatus with thick air-permeable
material is a major source of contamination whenever the housing is opened
for maintenance. It is a common phenomion that micro-organisms are
trapped in thick air-permeable material and multiply on the outer surface
(i.e., the surface which is further away from the irradiator) of the air-
permeable material if they are not destroyed by irradiation. Irradiation kills
the micro-organisms on the inner surface (i.e., the surface which is closer to
the irradiator) of the air-permeable material.
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Summar~of the Invention
It is an object of the present invention to enhance the micro-organisms
killing
capability of air filtering apparatus.
It is a further object of the present invention to minimize the emission of
irradiation from the air filtering apparatus without compromising the micro-
organism killing feature of the apparatus.
1o It is yet another object of the present invention to maximize the air
filtering
apparatus' ability to destroy micro-organism in the air-permeable material
while minimizing the chances of the air filtering apparatus becoming a
source of contamination.
The present invention describes an air filtering apparatus disposed within a
housing having at least an optical baffling means, an air-permeable material
downstream from the optical means, an irradiator within a sterilizing
chamber, and a blower further downstream from the irradiator. The air-
permeable material is the "see-through" type where light can pass through
2o the cross section areas of the material. Chemicals may be
added/incorporated/sprayed onto this air-permeable material to kill micro-
organisms when they come into contact with the air-permeable material. At
least one irradiator is arranged for directing ultraviolet radiation onto the
inner surfaces of the air-permeable material. With the "see-through" type
air-permeable material, the irradiation from the irradiator kills most of the
micro-organisms in the cross section areas including both surfaces of the
air-permeable material. As such, the improved air filtering apparatus of the
present invention is near germ free. The blower is provided to draw air
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through the optical baffling means, the air-permeable material and the
radiator. The optical baffling means minimizes the emission of radiation
from within the housing; similarly, the blower eliminates any radiation leak
from within the same housing.
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Brief Description of the Drawings
FIG. 1 shows a left side, isometric perspective view of the present invention.
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Detailed Description of the Invention
In FIG 1, the present invention describes an air filtering apparatus 10
disposed within a housing 4 having at least one optical baffling means 3, an
air-permeable material 5 downstream of the optical baffling means, at least
one irradiation means 6a within a sterilizing chamber 6 and downstream of
the air-permeable material 5, and a blower 7 downstream of the irradiation
means 6a. In the preferred embodiment of the present invention, the optical
baffling means comprises at least two plates spaced a small distance apart
1o and disposed in parallel to each other but preferably orthogonal to the
direction of air flow 1 through the air filtering apparatus 10. It should be
understood by one skilled in the art that many other optical baffling means
may be effectively employed. The optical baffling means 3 serves the
important function of minimizing the emission of radiation from within the
housing 4.
Referring again to FIG. 1, disposed downstream of the optical baffling
means 3 in the housing is the air-permeable material 5. The air-permeable
material has preferably a surface defining a major plane arranged for
2o filtering micro-organisms and dust particles contained in air flowing
through
the housing. The air-permeable material 5 is preferably the "see-through"
type where light can pass through the entire cross section areas of the
material. In the preferred embodiment of the present invention, honeycomb
nylon material may be used as the "see-through" air-permeable material. It
should be understood by one skilled in the art that other suitable material
may be used. Chemicals may be added/incorporated/sprayed onto the air-
permeable material 5 where micro-organisms can be killed when they come
into contact with such chemicals. As such, micro-organisms on both
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surfaces of the air-permeable material 5 are killed. In contrast with prior
art
air permeable materials which are thick, micro-organisms on the outer
surface (the surface further from the irradiator means 6a) are not killed. In
actual applications of air filtering apparatus with thick air-permeable
material, the air filtering apparatus is a major source of contamination as
irradiation fails to destroy micro-organisms, dust and dirt which are trapped
on the outer surface. This necessitates either the frequent cleaning of the
air-permeable material or the replacement thereof. No matter how
meticulous the maintenance of air filtering apparatus is carried out, micro-
1o organisms, dust and dirt fall out from the housing of the air filtering
apparatus. It would be desirable to have the least amount of micro-
organisms within the housing of the air filtering apparatus especially in
critical areas such as nurseries or near clean room environments. With the
see-through air-permeable material of the present invention, air filtering
apparatus maximizes its ability to destroy micro-organism in the air-
permeable material while minimizing the chances of the it becoming a
source of contamination..
Again in FIG. 1, the irradiation means 6a comprises at least one irradiator
2 o disposed in parallel with respect to the major plane and disposed within
the
sterilizing chamber 6 of the housing 4 for the entire cross section areas and
both surfaces of the air-permeable material 5 with ultraviolet irradiation so
as
to kill the micro-organisms. The ultraviolet irradiator may consist of at
least
one irradiator, and where there is more than one, one irradiator can be
mounted opposite each other but with their axes parallel to each other. In a
preferred embodiment, the two ultraviolet irradiators are close enough to
each other to ensure that an irradiation dose required for killing micro-
organisms is provided for the airstream that flows through the air permeable
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filter and through the sterilizing chamber 6. The irradiation means is
supported within the sterilizing chamber 6 such as to directly confront the
major plane of the air-permeable material 5. The sterilizing chamber 6 has
internal reflective surfaces. In the preferred embodiment of the present
invention, the internal surfaces of the sterilizing chamber 6 are coated with
an aluminum paint or use of materials with aluminum qualities for reflecting
the ultraviolet radiation within the sterilizing chamber 6 and directing the
radiation onto the air-permeable materials, thereby enhancing the
effectiveness of the radiation such that micro-organisms in the air-permeable
1o materials are killed. The longitudinal axis of the elongate type
ultraviolet
irradiation means 6a are disposed transversely with respect to the flow
direction of the air. Aluminum materials provide a high degree of reflectivity
for ultraviolet irradiation, hence increasing the intensity of ultraviolet
irradiation in the sterilizing chamber 6. Thus, all micro-organisms which may
possibly be present thereon, are destroyed. In an embodiment of this
invention, the air-permeable materials are configured for filtering micro-
organisms and dust particles from the air, the irradiation means comprises
ultraviolet irradiator 6a which emits radiation having wavelength of 253.7
nanometer (nm), and is arranged for directing ultraviolet radiation towards
2o the inner surface of the air permeable material 5 and sterilizing chamber
6.
Finally, a blower 7 disposed downstream of the irradiation means 6a draws
in air through the optical baffling means 3, the air-permeable material 5 and
the sterilizing chamber 6. The blower 7 serves a secondary function of
blocking the emission of radiation from the rear of the housing. It follows
that
it is highly unlikely that micro-organisms are present in the air leaving the
air
filtering apparatus. Furthermore, the emission of radiation is minimized or
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eliminated with the optical baffling means 3 in the rear and the blower in the
front of the housing.
The box housing 4 comprising the apparatus may be adapted for floor, wall
or ceiling suspended mounting, wherein air is drawn into the apparatus and
purified air is thrown back to the room space from the apparatus.
While the present invention has been described particularly with reference
to FIG 1 with emphasis on an apparatus for killing and/or removing micro-
organisms from air, it should be understood that the figure is for
illustration
1o only and should not be taken as limitation on the invention. In addition,
it is
clear that the apparatus of the present invention has utility in many
applications where purification of air is required. It is contemplated that
many changes and modifications may be made by one of ordinary skill in the
art without departing from the spirit and the scope of the invention as
described.
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